I used The Book Depository which Amazon purchased. It was the best (and the cheapest and the most expansive) website to purchase books in in my small european country until Amazon acquired it just to shut it down. Amazon doesn’t really operate in my country so I can’t even use it as an alternative. Still haven’t found another website as good as The Book Depository.
Psychonaut, DPH, heavymind, weirddalle, mspaint. All were once hidden gems of Reddit